Steam generator



Aug. 25, 1942. M. H. KUHNER ET AL STEAM GENERATOR Filed July 14, 1938 sSheets-Sheet "1 MAX H. KUHNEI? GUSTAV A. REHM an W g- 1942- M. H.KU'HNER ETAL' 2,293,833

STEAM GENERATOR Q Filed July 14, 19:58 3 Sheets-Sheet 2' MA x H. KUHNEEGUSTAV A. REHM annua Aug. 25, 1942. M. H. KUHNER ET AL STEAM GENERATORFiled July 14, 1938 3 Sheets-Sheet 3 OO0OOOOOODO OOOOOOOOOOOOOOOOOOOOOOODOOOOOOOOOOOOOOOOOO 000000000000000000000 000000000000000000000000000000000000000000 000000000000000000000 000000000000000000000OOOOOOOOOOOfi/OOOOOOOO 2 grvuc vvkvp H. K UHNER GUSTA v A. REE/MPatented Aug. 25, 1942 STEAM GENERATOR Max H. Kuhner and Gustav A. Rehm,Worcester, Mass., assignors to Riley Stoker Corporation, Worcester,Mass, a corporation of Massachusetts Application July 14, 1938, SerialNo. 219,214

8 Claims.

This invention relates to steam generators, and more particularly tosteam generators of the water tube type having water cooled walls at thesides of the combustion chamber.

It is one object of the invention to provide a water tube steamgenerator capable of producing steam at rates which are high incomparison with the floor space required for the installation.

It is a further object of the invention to provide a steam generatorparticularly adapted for operation with fuels such as oil, gas andpulverized coal, which are burned while in suspension in the combustionchamber.

It is a further object of the invention to provide a steam generatorhaving a simple and efiective means for supplying water to the lowerends of the water wall tubes.

It is a further object of the invention to provide a steam generatorwhich will be free from difliculties caused by priming and foaming.

With these and other objects in view, as will be apparent to thoseskilled in the art, the invention resides in the combination of partsset forth in the specification and covered by the claims appendedhereto.

Referring to the drawings illustrating one embodiment of the invention,and in which like reference numerals indicate like parts,

Fig. 1 is a longitudinal section through a steam generator, the sectionbeing taken on the line l-l of Fig. 3;

Fig. 2 is a, section on the line 2+2 of Fig. 1;

Fig. 3 is a section on the line 33 of Fig. 1; and

Fig. 4 is a fragmentary section on the line 4-4 of Fig. 1.

The embodiment illustrated comprises an upper transverse steam-and-waterdrum and a lower transverse Water drum therebeneath, these drums beingconnected by a bank of upright water tubes I2 and by a second bank ofupright water tubes l4 located in front of the tubes l2 and somewhatlarger in diameter than the tubes l2. The lower drum II is supported ona saddle I5, and the upper drum I0 is supported by the Water tubes. Awall I 6 is provided in the rear of the tube bank l2, and two wallsextend forwardly from the rear wall I6 on opposite sides of the watertubes to a transverse vertical plane located a substantial distance infront of the tube bank I4. A bridge wall I9 is provided in front of andbeneath the water drum H, and a front wall 20 is provided a substantialdistance in front of the side walls IT. The walls l6, l1, l9, and 20 arepreferably formed of a self-supporting type of refractory masonry.

Near the top of the front wall 20 there is provided a transverse header22 which is connected to the steam-and-water drum It) by means of tworows of water tubes 23, the upper row of tubes serving to support a roof24 of refractory material. A bank of water tubes 25 connects the lowerwater drum II with the header 22, these tubes being generally L-shaped,with upright lower portions located in front of the tubes l4, and withsubstantially horizontal upper portions which preferably slope slightlyupwardly to the header. There are three rows of these tubes 25, the rowsbeing comparatively closely spaced where the tubes are upright andcomparatively widely spaced where the tubes are substantiallyhorizontal. The tubes 25 in the front row are spaced apart more widelythan the others, to form a slag screen. A superheater 26 is mountedabove the upper sloping portions of the tubes 25.

The space 28 beneath the sloping portions of the tubes 25 is utilized asa combustion chamber into which a suitable fuel, such as pulverizedcoal, is introduced through one or more burner openings 29 in the frontwall 20. In order to enclose the combustion chamber on opposite sidesthere are provided two groups 30 and 3| of closely spaced upright watertubes located between the front wall 20 and the front edges of therefractory side walls I1. These tubes are exposed on their innersurfaces to the heat of combustion and they are enclosed on their outersides by means of refractory material 33. This refractory 33 may becomparatively thin, since it is supported and cooled by the water tubes.The outer surface of y the refractory 33 is substantially flush with theouter surface of the adjacent side wall l1, and each group of watertubes 30 and 3| is offset outwardly from the inner surface of theadjacent side wall. This increases consider-ably the volume of thecombustion space, and it utilizes the available floor space in anefficient manner. Furthermore, it facilitates the application of a steelcasing to the outside of the setting.

At each side of the combustion chamber 28 and near the top thereof weprovide a longitudinal header 35 to which the upper ends of the adjacentwater wall tubes 30 and 3| are connected. The ends of the tubes arepreferably staggered in order to maintain adequate ligaments in theheaders. A row of tubes 36 extends upwardly from each header to providesteam releasers therefor, certain of these tubes extending forwardly tothe header 22 and others extending rearwardly to enter thesteam-and-water drum ID in a circumferential row. As shown particularlyin Fig. 3, a space is provided between each side wall I! and theoutermost tubes in the tube banks 54 and 25, so that the tubes 35 mayextend along the inside of the side walls. These releaser tubes 36 areenclosed on their outer sides, in front of the side walls [1, by meansof refractory material 38, which may be comparatively thin.

As shown particularly in Fig. 2, each header 35 is located in a verticalplane which is intermediate the plane of the releaser tubes 36 and theplane of the water wall tubes 30 or 3|. In other Words, the header isoffset outwardly with respect to the releaser tubes and inwardly withrespect to the water wall tubes. One advantage of this construction isthat the header is located directly beneath the refractory material 38and serves to support the weight thereof.

In order to supply water to the water wall tubes 30 and 3| we provide alongitudinal lower header 40 located at the bottom of the combustionchamber 28 and at the side thereof adjacent to the tubes 30. The lowerends of the tubes 33 are connected to this header, and the lowerportions of the tubes 3| are bent laterally and extend at a slightdownward slope across the combustion chamber and are likewise connectedto the header. These sloping portions of the tubes 3| serve to supportrefractory material 42 which forms the floor of the combustion chamber.At the rear end of the header 4!] there is provided a header 43 which isconnected thereto at substantially a right angle and is arranged belowand parallel to the lower water drum II. The headers 48 and 43' may beintegral with each other, or they may be joined by welding orotherwise.Two rows of water tubes 44 connect the water drum H to the transverseheader 43.

When pulverized coal is to be used as a fuel, we preferably provide adepressed ash pocket 46 which extends across the rear of the combustionchamber directly in front of the bridge wall IS. A door 41 is providedin one or both sidewalls II to facilitate ash removal. One or more doors48 are provided in the front wall 20, so that a steam lance may beinserted to blow the ashes rearwardly from the floor 42 into the pocket45.

The refractory sidewalls I! extend forwardly for a substantial distancein front of the upright portions of the tubes 25, and hence aresubjected to considerable heat from. the combus-t tion chamber. In orderto prevent overheating and slagging of these walls we provide twoupright water tubes 50 at each side of the furnace, these tubes beinglocated adjacent to the forwardly extending portions of the wall II. Thelower portions of these tubes are bent rearwardly to connect with thelower drum I I, and the upper ends of the tubes are connected to theadjacent water wall header 35.

In order to direct the hot gases from the combustion chamber 28 intoproper contact with the water tubes, suitable baffles are provided. Abaffie 52 of refractory material is supported by the front row of tubesl4 and fills the spaces between the tubes in this row. This bafileextends upwardly from the lower drum H to the tops of the uprightportions of the rearmost tubes 25, and thence forwardly along thesloping portions of these tubes for about half their length. At eachside the upright portion of the baffle is supported by a tube 54connected at its lower end to the lower drum H and extending upwardly inalignment with the front row of tubes M. The upper portion of this tubeis bent rearward- 1y to avoid interference with the releaser tubes 36,as shown in Fig. 1, and enters the upper drum III in alignment with theupper ends of the rear row of tubes l4 and in the same circumferentialrow as the releaser tubes. A bafile 55 extends downwardly from the upperdrum [0 immediately in the rear of the front row of tubes l2, thisbaflle having forwardly and rearwardly projecting branches 56. Bafiles51 extend forwardly from the rear wall l6 into the tube bank [2 instaggered relation to the rearwardly projecting branches 55. A gasoutlet 58 is provided in the rear of the upper drum I0.

It will now be apparent that the hot gases from the combustion chamber28 will flow upwardly around the front of the baflie 52 and thencerearwardly and downwardly between the baflies 52 and 55. The gases willthen flow upwardly between the baffles 55 and 51 to the outlet 58. Mostof the soot and fly ash which is carried out of the combustion chamberby the gases will be deposited at the rear of the lower drum I I. Inorder to prevent this material from piling up against the header 43 apartition or plate 60 (Fig. 1) is provided which extends downwardly fromthe drum H in the rear of the tubes 44 and header 43. Access to the flyash deposit in the rear of this plate may be had through a door 6| inthe side wall IT. This side wall is also provided with a door 62 infront of the plate 60 through which access may be had to the header 43and tubes 44.

In order to prevent carry-over of excessive moisture from thesteam-and-water drum Hi to the superheater 26, we have shown atransverse drum 64 mounted above the drum I i] and connected to thesteam space thereof by means of tubes 65. The inlet ends of thesuperheater tubes 26 are connected to the upper portion of the drum 64.This steam drum 64 is provided with internal baflles 66 or othersuitable means to separate water from the steam which is delivered tothe drum by the tubes 65. The separated water is withdrawn from the drumthrough a tube 68 which leads downwardly along the outside of one sidewall I! to the lower water wall header 4D.

The operation of the invention will now be apparent from the abovedisclosure. Pulverized coal or other suitable fuel is introduced throughthe burner openings 29 and burns in suspension in the combustion chamber28. The hot gases flow upwardly into contact with the water tubes 25 andthe superheater 26, thence downwardly in contact with the water tubesl4, and thence upwardly in contact with the water tubes I2 and throughthe outlet 58 to a suitable stack. Since the baffle 52 is located behindthe water tubes 25, the upright portions of all these tubes are exposedto heat radiated rearwardly from the combustion chamber. This produces arapid upward circulation through these tubes and avoids any possibilityof steam-locking in the upper substantially horizontal portions of thetubes. Steam is generated very rapidly in the water tubes 25 and in theside wall tubes 30 and 3|, this steam flowing upwardly to thesteam-andwater drum [0 where most of the water is separated from thesteam. The steam then passes upwardly through the tubes 65 to the drum64 and thence to the superheater 2 6. Substantially all the water whichis carried by the steam into the drum 64 is deposited in the bottom ofthe drum and withdrawn through the tube 68. A sudden increase in thedemand for steam will not cause a flooding of the drum 64, since oneeffect of the steam generation in the water wall tubes 30 and 31 is tomaintain a high water velocity and a comparatively low static pressurein the header 40 to which the tube 68 is connected. Consequently waterwill escape from the drum 64 as fast as it can collect therein. Much ofthe ash from the fuel will be deposited directly in the ash pocket 46,from which it can be removed through the door 41, and such ash as fallsto the floor 42 can be blown rearwardly into this pocket by means of asteam lance. The fly ash which is carried over the top of the baflie 52by the hot gases will be deposited at the rear of the plate 60 and canbe removed through the door 6|. The tubes 44 and the transVerse header43 provide a simple means for supplying large quantities of water to thelower water wall header 4!], and they can be readily reached forinspection through the door 62. The front portions of the refractoryside walls I! are well protected by the water tubes 50 from excessiveheating or slagging. The arrangement of the water wall tubes 30 and 3|provides a maximum combustion space in a given floor area, andsimplifies the application of a steel casing. The upper headers 35, byreason of their offset positioning, provide ample support for the weightof the refractory 38. The close spacing of the upright portions of thetube rows 25 aids in increasing the space available for the rearwardtravel of the combustion flame, while the wide spacing of thesubstantially horizontal portions of these tube rows aids in chillingany slag particles which may arise with the combustion gases and avoidsthe tendency of such particles to accumulate on the Water tubes andsuperheater. The steam generator is of simple and inexpensiveconstruction, and yet capable of eflicient operation at comparativelyhigh rates.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

1. A steam generator comprising a transverse steam-and-water drum, atransverse water drum therebeneath, a bank of tubes connecting thedrums, means providing a combustion chamber in front of the tube bank,upright water wall tubes at one side of the combustion chamber, meansconnecting the upper ends of the water wall tubes to the steam-and-waterdrum, a longitudinally extending header to which the lower W ends of thewater wall tubes are connected, means to supply water from the waterdrum to the header, a steam drum mounted above the steam-and-water drum,means to conduct steam from the steam-and-water drum to the steam drum,means in the steam drum to separate water from the steam deliveredthereto, and a conduit through which the water thus separated may flowdownwardly to said header.

2. A steam generator comprising a transverse steam-and-water drum, atransverse water drum therebeneath, a bank of tubes connecting thedrums, means providing a combustion chamber in front of the tube bankarranged for the combustion of pulverized fuel in suspension, alongitudinally extending header located at the bottom of the combustionchamber and adjacent one side thereof, means to supply water from thewater drum to the header, means including a row of water tubes extendinglaterally from the header and across the bottom of the combustionchamber to provide a closed water cooled floor,

from the water drum, and means providing an ash pocket located betweenthe rear edge of the floor and the water drum and opening upwardly intothe rear portion of the combustion chamber.

3. A steam generator comprising a transverse steam-and-water drum, atransverse water drum therebeneath, a bank of tubes connecting thedrums, means providing a combustion chamber in front of the tube bankarranged for the combustion of pulverized fuel in suspension, alongitudinally extending header located at the bottom of the combustionchamber and adjacent one side thereof, means to supply water from thewater drum to the header, a row of water tubes extending upwardly fromthe header to provide a water cooled wall for the adjacent side of thecombustion chamber, a row of water tubes extending laterally from theheader and across the bottom of the combustion chamber to provide awater cooled floor and thence upwardly to provide a water cooled wallfor the other side of the combustion chamber, the rear edge of the floorbeing spaced forwardly from the water drum, and means providing an ashpocket between the rear edge of the floor and the water drum.

4. A steam generator comprising a transverse steam-and-water drum, atransverse water drum therebeneath, a bank of tubes connecting thedrums, refractory side walls located on opposite sides of the tubebankand extending forwardly beyond the tube bank, means providing acombustion chamber in front of the tube bank arranged for the combustionof pulverized fuel in suspension, a longitudinally extending lowerheader located at the bottom of the combustion chamber and adjacent oneside thereof, means to supply water from the water drum to the header,an upper longitudinal header at each side of the combustion chamber, arow of water tubes extending upwardly from the lower header to the upperheader on the same side to provide a water cooled wall for the adjacentside of the combustion chamber, a row of water tubes extending laterallyfrom the lower header and across the bottom of the combustion chamber toprovide a water cooled floor and thence upwardly to provide a watercooled wall for the other side 'of the combustion chamber, the rear edgeof the floor being spaced forwardly from the water drum, and meansproviding an ash pocket in the rear of the floor and between theforwardly extending portions of the refractory side walls.

5. A steam generator comprising a transverse steam-and-water drum, atransverse water drum therebeneath, a bank of tubes connecting thedrums, refractory side walls located on opposite sides of the tube bankand extending forwardly beyond the tube bank, means providing acombustion chamber in front of the tube bank, a longitudinal header ateach side of the combustion chamber adjacent the upper portion thereof,a row of water wall tubes at each side of the combustion chamber toprovide water cooled walls in front of the refractory walls, the waterwall tubes being connected at their upper ends to the headers, means tosupply water from the water drum to the lower ends of the water walltubes, and water tubes leading from the end portions of the water drumto the rear portions of the headers to protect the forwardly extendingportions of the refractory side walls from the heat of combustion.

6. A steam generator comprising a transverse t e e edge o e oor beingSpaced forwardly 7 steam-and-water drum, a transverse water drumtherebeneath, a bank of tubes connecting the drums, refractory sidewalls located on opposite sides of the tube bank, means providing acombustion chamber in front of the tube bank, a row of water wall tubesat each side of the combustion chamber to provide water cooled walls infront of the refractory walls, each row of water wall tubes beinglocated in a plane which is offset outwardly from the plane of the innersurface of the adjacent refractory wall, means to supply water from thewater drum to the water wall tubes, longitudinal headers to which theupper ends of the water wall tubes are connected, each header beinglocated in a vertical plane intermediate the plane of the water walltubes and the plane of the inner surface of the refractory wall,releaser tubes extending upwardly from the headers and thence rearwardlyalong the inner surfaces of the refractory walls to the end portions ofthe steam-and-water drum, and refractory material located outside thereleaser tubes in front of the refractory walls and above the headers.

7. A steam generator comprising a transverse steam-and-water drum, atransverse water drum therebeneath, a bank of tubes connecting thedrums, refractory side walls located on opposite sides of the tube bank,means providing a combustion chamber in front of the tube bank, a row ofwater wall tubes at each side of the combustion chamber to provide watercooled walls in front of the refractory walls, means to supply waterfrom the water drum to the water wall tubes, longitudinal headers towhich the upper ends of the water wall tubes are connected, releasertubes extending upwardly from the headers and thence rearwardly betweenthe tube bank and the refractory walls to connect with the end portionsof the steam-and-water drum, a baflle of refractory material extendingupwardly from the water drum, and two water tubes extending upwarllyfrom the water drum in supporting relation to the sides of the baflle,the upper portions of the last mentioned tubes being bent rearwardly andentering the steam-and-water drum below and rearwardly of the releasertubes.

8. A steam generator comprising a transverse steam-and-water drum, atransverse water drum therebeneath, a bank of tubes connecting thedrums, refractory side walls located on opposite sides of the tube bank,means providing a combustion chamber in front of the tube bank, a row ofwater wall tubes at each side of the combustion chamber to provide watercooled walls in front of the refractory walls, means to supply waterfrom the water drum to the water wall tubes, longitudinal headers towhich the upper ends of the water wall tubes are connected, releasertubes extending upwardly from each header and thence rearwardly betweenthe tube bank and the adjacent refractory wall to enter the adjacent endportion of the steam-and-water drum in a circumferential row, a baffleof refractory material extending upwardly from the water drum,. and twowater tubes extending upwardly from the water drum in supportingrelation to the sides of the bafile, the upper portion of each of thelast mentioned tubes being bent rearwardly and entering thesteam-and-water drum below and rearwardly of the adjacent releaser tubesand in the same circumferential row therewith.

MAX H. KUHNER. GUSTAV A. REHM.

7 CERTIFICATE OF CORRECTION. Patent no..2,:295,s55 7 August 25, '19u2.

MAX H. KUHNER, ET AL.

It is hereby certified thet error appears in the printed specificationof the above numbered. patent requiring correction as follows Page 2,first column; line 50, for the words "the floor of? read "deleted floorfor--; page 11., second column, line 5, for upwarlly read "upwardly";and that the seid' Letters Patent should be bead with thiscorrection'therein that .the same may conform to the record of the casein the Patent Office, v

Signed and sealed this 29th day of September, A. D. 19).;2.

Henry Van Arsdale, (Seal) Acting Comissioner of Patents.

